This invention relates to wind power systems, and more particularly to a method and apparatus for controlling the level of power transferred through a stand-alone wind power generating system.
Wind power generating systems convert available wind power to electrical power. Many are stand-alone in that they are not connected to utility systems. Typically, such stand-alone systems incorporate large generators and large energy storage sub-systems to provide sufficient electrical energy during periods of low wind or no wind conditions. The cost of such equipment can, however, be somewhat expensive.
It has been found that maximizing the energy generated at low wind speeds is critical to system optimization, especially in minimizing energy storage size and cost. Often, in an effort to reduce the size of the generator and the energy storage sub-system such generating systems will incorporate blade pitch control so as to maximize the energy generated at low wind speeds. While this approach can result in a reduction of the size of the generator and storage sub-system, a problem arises in that this approach also severely limits turbine power transfer, causing the amount of the reduction to be limited.